80. Assume ecsql1.employee_donations has 6 observations, and qtr1 has 6 values listed below: 100
200
300
.
150
50


What is the value of donation_tot after the 5th DATA step iteration?
data work.donations;

set ecsql1.employee_donations (drop=qtr2-qtr4);
retain donation_tot 1000;
donation_tot + qtr1;
run;

a) 0
b) 750
c) 1750
d) Data step fails due to errors
Answer: C


不是说+ - * / 碰到missing value，返回也是missing value码？